The present invention relates to a view port for observing ingot growing and an ingot growth apparatus including the view point.
A silicon single crystal ingot which is generally material of a wafer is prepared using a Czochralski method (CZ method).
The CZ method is an ingot growing method that causes an ingot to be grown to have an predetermined diameter by putting silicon into a quartz crucible, heating the quartz crucible causing the silicon to be melted, and then rotating and gradually pulling up seed crystal in a state of contacting the seed crystal with silicon melt to solidify the silicon melt into solid on the seed single crystal surface.
Such an ingot growth apparatus is provided in the inside of a chamber. The chamber provides a space in which predetermined processes are performed for growing the ingot for a wafer which is used in material of an electronic component such as a semiconductor.
In addition, a separate view port is installed on a side of the chamber for observing the ingot which grows in the inside of the chamber, since the chamber is sealed to prevent contaminant from entering the inside of the chamber and to maintain internal atmosphere.
It is possible to be observed growing of the ingot by the naked eyes through such a view port as well as to be measured process data such as a diameter of the growing ingot and a melt gap by a diameter measurement sensor, a melt gap (M/G) measurement sensor, or the like.
Hereinafter, accurate measuring of the process data in the inside of the chamber is an important factor in determining the quality of ingot, since a process condition such as ingot pulling speed, heater power, or the like is determined in consideration of the real-time process data measured as above.
But, the problem that a glass of the view point is contaminated is occurred by gas or vaporized dopant generated in the quartz crucible in the inside of the chamber.
Particularly, it is difficult to observe the inside of the chamber as well as an error in the process data, such as measured diameter through the view port is generated, since the vaporized dopant causes the lower surface of the glass to be contaminated and to be opaque.
In order to prevent such an error, a method for adjusting movement speed of a sensor, sensitivity of sensor, or the like is proposed, but the reduction effect of the error is insufficient.
Therefore, the problem that the quality of the grown ingot is degraded occurs, since the process condition is determined by such an inaccurate process data.